“Laborsaving Cam Wheel Structure,” developed by the present inventor and disclosed in the ROC Patent No. M297612 on Sep. 11, 2006, is formed of a fixed member and a movable member abutted against and having an axle hole a mounting hole, respectively. The fixed member and movable member each has two slopes spirally running in reversed directions on the respective inner side, such that each slope has a peak end an adjacent root end. The peak and root ends of the fixed member are respectively abutted against those of the movable member such that when one of the two members rotates, the two peak ends move along the corresponding slope of the neighboring member from the peak to root ends.
However, there is room for improvement to avoid the jerk during the rotation between 150 to 180 degrees.